A Late Holocene geomagnetic secular variation record from Erhai Lake, southwest China

Hyodo, Masayuki; Yoshihara, Arata; Kashiwaya, Kenji; Okimura, Takashi; Masuzawa, Toshiyuki; Nomura, Ryotaro; Tanaka, Shingo; Xing, Tang Bang; Qing, Liu Su; Jian, Liu

doi:10.1046/j.1365-246x.1999.00764.x

Cited by 26 publications

(25 citation statements)

References 9 publications

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“…It should be pointed out that the consistent age between cellulose-rich fraction and humic acid fraction extracted from plant fragment indicates no postburial effect and negligible vertical movement for humic acid fraction. It is also worth to note that our measured celluloserich fraction age (5050 ± 40 yr BP) is older than previous date, 4440 ± 130 yr BP, obtained in the same horizon by Hyodo et al (1999). The reason for the difference between the two measurements remains unclear.…”

Section: Radiocarbon Datescontrasting

confidence: 63%

“…3b. It can be found that there is a linear correlation between 14 C age and depth for the terrestrial macrofossils (plant fragment and shell) in ER3 and ER24 measured in this study and Hyodo et al (1999). Although there is a gap between 115 and 251 cm-deep, the best fitting gives the linear correlation (dashed line in Fig.…”

Section: Age and Depth Correlation Of Terrestrial Macrofossilssupporting

confidence: 51%

“…About 5~10 g dried bulk sediment samples were used for the extraction of the three humus 14 C dates shown as Italic font are from Hyodo et al (1999) and others are from this study.…”

Section: Samples and Experimentsmentioning

confidence: 99%

“…From δ 13 C values of organic matter in the Erhai Lake, less negative values below 100 cm (corresponding to 2000 yr BP) may imply small contribution of terrestrial organic matter. Hyodo et al (1999) found that the curves of ARM intensity and ARM intensity normalized by susceptibility (ARM/susceptibility) show a sudden increase at around 100 cm (corresponding to ca. 2000 yr BP) and explained it to be related to a sudden change in grain size.…”

Section: Variations Inmentioning

confidence: 99%

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Variations in radiocarbon ages of various organic fractions in core sediments from Erhai Lake, SW China.

Zheng

2003

Geochem. J.

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Section: Radiocarbon Datescontrasting

confidence: 63%

Section: Age and Depth Correlation Of Terrestrial Macrofossilssupporting

confidence: 51%

“…About 5~10 g dried bulk sediment samples were used for the extraction of the three humus 14 C dates shown as Italic font are from Hyodo et al (1999) and others are from this study.…”

Section: Samples and Experimentsmentioning

confidence: 99%

Section: Variations Inmentioning

confidence: 99%

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Variations in radiocarbon ages of various organic fractions in core sediments from Erhai Lake, SW China.

Zheng

2003

Geochem. J.

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“…Around 7000 BC all data series consistently show a clear inclination minimum, which is predicted by pfm9k.1a and CALS10k.OL2c, but not by SHA.DIF.14k. This is because at that time the few available data (only 355 values for the whole interval of 12000 BC to 6000 BC) come from a small area at the western coast (Stockhausen 1998); WAI -Lake Waiau, Hawaii (Peng & King 1992); GNO -Lake Gnotuk, Australia (Barton & McElhinny 1981) and ERH -Erhai Lake, China (Hyodo et al 1999). (A colour version of this figure is available in the online version.)…”

Section: Discussionmentioning

confidence: 99%

Limitations in paleomagnetic data and modelling techniques and their impact on Holocene geomagnetic field models

Panovska

Korte

Finlay

et al. 2015

Geophysical Journal International

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S U M M A R YCharacterization of geomagnetic field behaviour on timescales of centuries to millennia is necessary to understand the mechanisms that sustain the geodynamo and drive its evolution. As Holocene paleomagnetic and archeomagnetic data have become more abundant, strategies for regularized inversion of modern field data have been adapted to produce numerous timevarying global field models. We evaluate the effectiveness of several approaches to inversion and data handling, by assessing both global and regional properties of the resulting models. Global Holocene field models cannot resolve Southern hemisphere regional field variations without the use of sediments. A standard data set is used to construct multiple models using two different strategies for relative paleointensity calibration and declination orientation and a selection of starting models in the inversion procedure. When data uncertainties are considered, the results are similar overall regardless of whether we use iterative calibration and reorientation, or co-estimation of the calibration and orientation parameters as part of the inversion procedure. In each case the quality of the starting model used for initial relative paleointensity calibration and declination orientation is crucial and must be based on the best absolute information available. Without adequate initial calibration the morphology of dipole moment variations can be recovered but its absolute value will be correlated with the initial intensity calibrations, an effect that might be mitigated by ensuring an appropriate fit to enough high quality absolute intensity data with low uncertainties. The declination reorientation mainly impacts regional field structure and in the presence of non-zonal fields will result in a non-zero local average. The importance of declination orientation is highlighted by inconsistencies in the West Pacific and Australian sediment records in CALS10k.1b model. Great care must also be taken to assess uncertainties associated with both paleomagnetic and age data and to evaluate the effects of poor data distribution. New consistently allocated uncertainty estimates for sediment paleomagnetic records highlight the importance of adequate uncertainties in the inversion process, as they determine the relative weighting among the data and overall normalized misfit levels which in turn influence the complexity of the inferred field models. Residual distributions suggest that the most appropriate misfit measure is the L 1 norm (minimum absolute deviation) rather than L 2 (least squares), but this seems to have relatively minor impact on the overall results. For future Holocene field modelling we see a need for comprehensive methods to assess uncertainty in individual archeomagnetic data so that these data or models derived from them can be used for reliable initial relative paleointensity calibration and declination orientation in sediments. More work will be needed to assess whether co-estimation or an iterative approach to inversion is more efficient overall...

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High‐resolution paleomagnetic and sedimentological investigations on the Tibetan Plateau for the past 16 ka cal B.P.—The Tangra Yumco record

Henkel

Haberzettl

St‐Onge

et al. 2016

Geochem Geophys Geosyst

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The spatial distribution of paleomagnetic secular variation (PSV) records on the Tibetan Plateau and adjacent areas covering the Holocene and Late Glacial is sparse. In order to reconstruct PSV in this area, a piston core covering the past 17.5 ka cal B.P. retrieved from Lake Tangra Yumco, southern‐central Tibetan Plateau, was analyzed. In the laminated sediments, several event layers are intercalated. Those were identified by sedimentological analysis and excluded for age‐depth modeling and interpretation. Paleomagnetic measurements on u‐channels reveal two contrasting core sections. The lower section (dated to 17.5–15.9 ka cal B.P.) is very coarse grained (up to 220 µm) and characterized by low intensities (0.8 mA m−1) and high maximum angular deviation values (mean 25°), making it unsuitable for PSV reconstruction. In contrast, the upper unit (dated to <15.9 ka cal B.P.) yields ideal properties with a well‐defined magnetization carried by low‐coercivity minerals in the pseudo single domain state making those younger sediments a proper record for PSV studies. The robustness of the PSV reconstruction for the past 3000 years is highlighted by a comparable inclination and declination pattern of three short sediment cores (2 m) from Tangra Yumco. On a regional scale, the obtained inclination signal for the past 15.9 ka cal B.P. is in good agreement with the Lake Baikal record (3000 km to the North), PSV stack for East Asia, as well as with predictions of geomagnetic field models. This study is a step forward in constructing a PSV reference curve for central Asia.

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A Late Holocene geomagnetic secular variation record from Erhai Lake, southwest China

Cited by 26 publications

References 9 publications

Variations in radiocarbon ages of various organic fractions in core sediments from Erhai Lake, SW China.

Variations in radiocarbon ages of various organic fractions in core sediments from Erhai Lake, SW China.

Limitations in paleomagnetic data and modelling techniques and their impact on Holocene geomagnetic field models

High‐resolution paleomagnetic and sedimentological investigations on the Tibetan Plateau for the past 16 ka cal B.P.—The Tangra Yumco record

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